in southern israel, a hamas rocket ripped a hole through an empty school. police say it was one of at least 75 that landed overnight. israel's new iron dome defense system is helping keep casualty numbers low. >> i feel confident that the iron dome is going to be protecting us. >> reporter: the missile shield is successfully taking out hamas rockets before they land in populated areas like jerusalem and tel aviv. egypt is take a leading role in trying to broker a cease-fire between hamas and israel. president obama is traveling in asia and has been on the phone with leaders in the region. >> israel has every right to expect that it does not have missiles fired into its territory. >> reporter: israel is move troops to the border and has not ruled out a ground invasion. >> ground invasion is very possible but it's not i don't think what either party would like to see. >> reporter: president obama said a ground war would threaten future peace talks. israel is likely to face more international pressure to end the fighting as civilian casualties climb in gaza. d